极薄带异步轧制滑移带演化的晶体塑性有限元分析

Crystal plasticity finite element method(CPFEM)analysis for slip band development in foil asymmetrical rolling

以单层晶极薄带轧制为研究对象,采用多尺度晶体塑性有限元方法模拟其在拉-压-剪复合应力状态下的宏观剪切带和微观滑移带演化,优化极薄带材轧制工艺。在微观层次上,每个晶粒被离散成若干个有限元单元,且每个积分点采用单晶体本构模型。宏-微观层次模拟的共同特征是滑移带演化高度的各向异性和局部化,微观层次的模拟更加明显。结果表明:新剪切带随轧制区施加额外剪切变形而形成,在拉-压-剪复合应力下,强剪切造成已缩窄的主次剪切带随轧制压下的增大而又扩展。单系滑移带在各变形晶粒内的演化差异很大,存在主次滑移,随压-剪复合应力状态的增强而形成亚滑移带。在拉-压-剪复合应力下,单滑移扩展和叠加形成贯穿晶界的累积滑移带,晶界起到很好的滑移承载和传递作用。

A multi-scale crystal plastic finite element method is used to simulate the evolution of macroscopic shear band and microscopic slip band under tension-compression-shear combined stress optimizing the rolling process of single crystal foil rolling.At the microscopic level,each grain is separated into several finite element elements,and a single crystal constitutive model is used for each integral point.The common feature predicted by simulations at the macro-micro level is the anisotropy and localization of slip zone evolution height,more clearly revealed by simulations at the microscale.The results show that a new shear band is formed with additional shear deformation applied to the rolling zone.The narrowed primary and secondary shear bands to re-expand with the increase of rolling reduction under the combined stress state of tensioncompression-shear.There are primary and secondary slips in which evolution of single-system slip bands varies greatly among the deformed grains,with sub-slip bands formed with the increase of compression-shear stress states.The single slip expands and superposes to form a cumulative slip band across the grain boundary,and the grain boundary plays an important role in carrying and transferring the slip under the combined stress state of tension-compression-shear.